Assessing albedo dynamics and its environmental controls of grasslands over the Tibetan Plateau

Land surface albedo, as an essential biophysical factor, plays an essential role in surface energy balance. Identifying environmental drivers of albedo in the Tibetan Plateau (TP) helps to understand the role of the third pole in responding to environmental change and regulating regional climate. Based on remotely sensed data of albedo, Normalized Difference Vegetation Index (NDVI), snow cover, and soil moisture, this study investigated the effects of land cover (i.e., vegetation, snow) and soil on albedo from the perspectives of spatial, temporal, and spectral (visible, near-infrared, and shortwave) changes of albedo. Generally, changes in shortwave (SW) albedo were primarily driven by changes in snow cover during the growing season (from May to September), predominantly in May and June. The NDVI had larger contributions to visible (VIS) albedo change and was identified as the foremost important driver for VIS albedo in July and August. The correlations between the nearinfrared (NIR) albedo and NDVI were positive in the mid- and late growing season in eastern TP. Soil moisture was negatively correlated with albedo throughout the growing season and was identified as the foremost important driver in August. The NIR albedo was more susceptible than the VIS albedo to changes in soil moisture. The correlations between NDVI and albedo varied across different categories of aridity caused by changing correlations between NIR albedo and NDVI along the aridity gradients, and consequently the VIS and NIR albedo counterbalance can further limit the contributions of vegetation greenness on SW albedo in sub-humid and humid region. Our findings are expected to improve understandings of energy budget simulations over TP region in land surface models.

Automated summary

This study investigated the environmental drivers of albedo in the Tibetan Plateau based on remotely sensed data, revealing the significant impacts of snow cover, vegetation index, and soil moisture on albedo changes in different seasons and spectral bands. The findings are expected to enhance the understanding of energy budget simulations over the Tibetan Plateau region in land surface models.